Copolymers of ethylene with c3-c12 α-olefins

ABSTRACT

Copolymers of ethylene with C 3 -C 12  α-olefin have a polydispersity Mw/Mn of ≦10, a density of from 0.85 to 0.95 g/cm 3 , a proportion of from 1 to 40% by weight of comonomer and a molar mass Mn above 150,000 g/mol and a comonomer composition distribution breadth index above 70%. A process for their preparation is described, as are their use and fibers, moldings, films and polymer mixtures comprising these copolymers.

The invention relates to copolymers of ethylene with C₃-C₁₂ α-olefins,which have a polydispersity Mw/Mn of ≦10, a density of from 0.85 to 0.95g/cm³, a proportion of from 1 to 40% by weight of comonomer and a molarmass Mn above 150,000 g/mol and a comonomer composition distributionbreadth index above 70%, and to a process for their preparation and totheir use, and also to fibers, moldings, films and polymer mixturescontaining these copolymers.

Copolymers of ethylene with higher α-olefins, such as 1-butene,1-pentene, 1-hexane or 1-octane, known as LLDPE (linear low-densitypolyethylene), may be prepared, for example, using traditional ZieglerNatta catalysts based on titanium, or else using metallocenes. Theformer give LLDPE with a broad composition distribution and with arelatively broad distribution of average molar mass, e.g. Mw/Mn>3, whereMn is the number-average and Mw the weight-average molecular weight. Onemeasure of the composition distribution breadth is the CDBI, thecomposition distribution breadth index. The CDBI is defined as thepercentage by weight of the copolymer molecules whose comonomer contentis within 50% of the average comonomer content. It may be determinedeasily by TREF (temperature rising elution fraction) analyses (Wild et.al. J. Poly. Sci., Poly. Phys. Ed. Vol. 20, (1982), 441, or U.S. Pat.No. 5,008,204).

In contrast, metallocene catalysts, for example, may be used to obtainethylene copolymers with a narrow molar mass distribution and aCDBI>50%. These LLDPEs have particularly advantageous mechanicalproperties. Copolymerization with higher α-olefins frequently given riseto a reduced molecular weight. At higher concentrations of comonomer,chain termination is generally increasingly favoured, and the molecularweight thus reduces (U.S. Pat. No. 5,625,016 states that Mn is belowabout 50,000). The low-molecular-weight copolymers may firstly give riseto deposits in the reactor during the polymerization and can secondlygive rise to undesirable product properties, e.g. tacky surfaces. LLDPEswith a high molecular weight and high comonomer content are, incontrast, difficult to prepare.

WO-A-98/44011 describes ethylene polymers with at least one alpha olefinhaving at least 5 carbon atom and with a melt index MI of from 0.1 to15, a CDBI of at least 70%, a density of from 0.91 to 0.93 g/ml, a hazevalue below 20%, a melt index ratio MIR of from 35 to 80, an averagemodule of from 20,000 to 60,000 psi and a defined ratio of modulus todart impact strength. The polymers obtained moreover contain essentiallyno unsaturated end groups (page 9, line 16 to 23).

WO-A-93/12151 describes ethylene copolymers with alpha olefins having atleast 10 carbon atoms. These have a density of from 0.85 to 0.95 g/cm³,an average molecular weight M_(w) of from 30,000 to 1,000,000 Dalton anda polydispersity of from 2 to 4.

It is an object of the present invention to find copolymers with highmolar masses, a high proportion of comonomer and a high CDBI, and asuitable preparation process for these.

We have found that this object is achieved by copolymers of ethylenewith C₃-C₁₂ α-olefins, which have a polydispersity Mw/Mn of from 1 to10, density of from 0.85 to 0.95 g/cm³, a proportion of from 1 to 40 molof comonomer per . . . and a molar mass Mn above 150,000 g/mol and amonomer composition distribution breadth index above 70%.

We have also found a process for preparing the novel ethylenecopolymers, which comprises carrying out the process in the presence ofthe following components:

-   -   (A) Substituted monoindenyl- or monofluorenylchromium complexes        of formula I    -   where:    -   Y has the following formula II    -   where    -   Z is an unsubstituted, substituted or condensed heteroaromatic        ring system,    -   X, independently of one another, are fluorine, chlorine,        bromine, iodine, hydrogen, C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl,        C₆-C₂₀-aryl, alkyaryl having from 1-10 carbon atoms in the alkyl        radical and from 6-20 carbon atoms in the aryl radical, NR⁷R⁸,        OR⁷, SR⁷, SO₃R⁷, OC(O)R⁷, CN, SCN, β-diketonate, CO, BF₄—, PF₆—,        or bulky noncoordinating anions,    -   R¹-R⁸, independently of one another, are hydrogen, C₁-C₂₀-alkyl,        C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1 to 10        carbon atoms in the alkyl radical and from 6-20 carbon atoms in        the aryl radical, SiR⁸ ₃, where the organic radicals R¹-R⁸ may        also have halogen substitution and any two geminal or vicinal        radicals R¹-R⁸ may also have been bonded to give a 5- or        6-membered aromatic or aliphatic ring,    -   R⁹, independently of one another, are hydrogen, C₁-C₂₀-alkyl,        C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1 to 10        carbon atoms in the alkyl radical, and from 6-20 carbon atoms in        the aryl radical, and where in each case two geminal radicals R⁹        may also have been bonded to give a five- or six-membered ring,    -   n is 1, 2 or 3, and    -   m is 1, 2 or 3,    -   and    -   (B) if desired, one or more activator compounds.

We have also found polymer mixtures which comprise at least one novelcopolymer of ethylene with C₃-C₁₂ α-olefins, and moreover fibers, filmsand moldings which comprise the novel copolymers of ethylene with C₃-C₁₂α-olefins as a substantial component.

The use of the novel copolymers with ethylene with C₃-C₁₂ α-olefins forproducing fibers, films or moldings has also been found.

For the purposes of the present invention and as is known, HLMFR is highload melt flow rate and is always determined at 190° C. with a load of21.6 kg (190° C./21.6 kg).

The comonomer distribution breadth of the novel copolymers mayadvantageously be described via the standard deviation of the weightedaverage elution temperature Ta, as can be determined by TREF. TREF isdescribed, for example, in wild, Advances in Polymer science, 98, pp.1-47, 57 p, 153, 1992. The weighted average elution temperature (Ta) andthe standard deviation (S) are used as follows (see also Bevington,McGraw-Hill, Data Reduction and Error Analysis for the physicalSciences, 1969).

The novel copolymer of ethylene with C₃-C₁₂ α-olefins has apolydispersity Mw/Mn of ≦10, preferably from 2 to 4 and particularlypreferably from 2 to 3.5, a density of from 0.85 to 0.95 g/cm³,preferably from 0.88 to 0.93 g/cm³, and a molar mass Mn above 150,000g/mol, preferably above 200,000 g/mol, and very particularly preferablyabove 250,000 g/mol. Its HLMFR is from 0.001 to 20 g/10 min, preferablyfrom 0.01 to 15 g/10 min, and the comonomer composition distributionbreadth index is above 70%, preferably above 80% and particularlypreferably above 90%.

A preferred embodiment of the novel copolymer has a comonomercomposition distribution breadth index above 90% and a polydispersityMw/Mn of from 2 to 4.

The novel copolymers preferably have a vinyl- or vinylidene-terminatedend group.

Possible comonomers which may be present alongside ethylene in the novelcopolymer, individually or mixed with one another, are any of theα-olefins having from 3 to 12 carbon atoms, e.g. propene, 1-butene,1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and1-decene. A preferred copolymerized comonomer unit present in theethylene copolymer is that of α-olefins having from 3 to 9 carbon atoms,such as butene, pentene, hexene, 4-methyl-pentene or octene. Particularpreference is given to α-olefins selected from the group consisting ofpropene, 1-butene, 1-hexene and 1-octene. The amount of the comonomersas copolymerized in the novel ethylene copolymers is generally from 1 to40% by weight, preferably from 5 to 20% by weight and in particular from10 to 20% by weight, based in each case on the ethylene copolymer.

The ethylene copolymers may in principle be prepared using any catalystor catalyst system which give rise to products with the required narrowmolar mas distribution. These catalysts are generally those known assingle-site-catalysts, preferably the substituted monoindenylchromiumcomplexes described above of the formula I, where at least one of thesubstituents on the five-membered indenyl ring has an unsubstituted,substituted or condensed, heteroaromatic ring system.

In the complexes according to the invention the indenyl ring has η⁵bonding to the chromium center. The substituents on the indenyl systemmay also form a benzindenyl system or a fluorenyl system.

Y is a substituted indenyl system which has an unsubstituted,substituted or condensed, heteroaromatic ring system which may havecoordinated bonding or be uncoordinated. The heteroaromatic ring systempreferably has intramolecular coordination to the chromium center.

Z is an unsubstituted, substituted or condensed, heterocyclic aromaticring system which may contain, besides carbon ring members, heteroatomsselected from the group consisting of oxygen, sulfur, nitrogen andphosphorus. Examples of 5-membered ring heteroaryl groups, in which thering members present, besides carbon atoms, may be from one to fournitrogen atoms or from one to three nitrogen atoms and/or a sulfur oroxygen atoms, are 2-furyl, 2-thienyl, 2-pyrrolyl, 3-isoxazolyl,5-isoxazolyl, 3-isothiazolyl, 5-isothiazolyl, 1-pyrazolyl, 3-pyrazolyl,5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-thiazolyl,4-thiazolyl, 5-thiazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl,1,2,4-oxadiazol-3-yl, 1,2,4-oxadiazol-5-yl, 1,3,4-oxadiazol-2-yl and1,2,4-triazol-3-yl. Examples of 6-membered heteroaryl groups, which maycontain from one to four nitrogen atoms and/or a phosphorus atom, are2-pyridinyl, 2-phosphabenzolyl 3-pyridazinyl, 2-pyrimidinyl,4-pyrimidinyl, 2-pyrazinyl, 1,3,5-triazin-2-yl and 1,2,4-triazin-3-yl,1,2,4-triazin-5-yl and 1,2,4-triazin-6-yl. The 5-membered-ring and6-membered-ring heteroaryl groups here may also have substitution byC₁-C₁₀-alkyl, C₆-C₁₀-aryl, alkylaryl having from 1 to 10 carbon atoms inthe alkyl radical and from 6 to 10 carbon atoms in the aryl radical,trialkylsilyl or halogens, such as fluorine, chlorine or bromine, orhave been condensed with one or more aromatic systems or heteroaromaticsystems. Examples of benzo-condensed 5-membered heteroaryl groups are2-indolyl, 7-indolyl, 2 cumaronyl, 7-cumaronyl, 2-thionaphthenyl,7-thionaphthenyl, 3-indazolyl, 7-indazolyl, 2-benzimidazolyl and7-benzimidazolyl. Examples of 6-membered benzo-condensed heteroarylgroups are 2-quinolyl, 8-quinolyl, 3-cinnolyl, 8-cinnolyl, 1-phthalazyl,2-quinazolyl, 4-quinazolyl, 8-quinazolyl, 5-quinoxalyl, 4-acridyl,1-phenanthridyl and 1-phenazyl. The terminology and numbering for theheterocyclic systems has been taken from L. Pieser and K. Fieser,Lehrbuch der organischen Chemie, 3rd revised edition, Verlag Chemie,Weinheim 1957. Preference is given here to simple system which are easyto obtain and inexpensive and have been selected from the followinggroup:

Appropriate selection of the radicals R¹⁰-R¹⁹ can effect the activity ofthe catalyst and the molecular weight of the resultant polymer. Possiblesubstituents R¹⁰-R¹⁹ are the radicals described for R¹—R⁸ and halogens,e.g. fluorine, chlorine or bromine, and it is also possible, if desired,for two vicinal radicals R¹⁰ to R¹⁹ to have been bonded to give a 5- or6-membered ring and to have substitution by halogens, such as fluorine,chlorine or bromine. Preferred radicals R¹⁰-R¹⁹ are hydrogen, methyl,ethyl, n-propyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, vinyl, allyl, benzyl, phenyl, naphthyl, biphenyl and anthranyl,and also fluorine, chlorine and bromine. Possible organosiliconsubstituents are in particular trialkylsilyl having from 1 to 10 carbonatoms in the alkyl radical, and in particular trimethylsilyl. Z is veryparticularly preferably unsubstituted or substituted, e.g.alkyl-substituted, quinolyl, in particular with linking at position 8,for example 8-quinolyl, 8-(2-methylquinolyl),8-(2,3,4-trimethylquinolyl) or 8-(2,3,4,5,6,7-hexamethylquinolyl. Thiscan be prepared very easily and also gives very good activities.

Various properties of the catalyst system may also be altered by varyingthe substituents R¹-R⁸. The number and type of substituents, inparticular R¹ and R⁷, can affect the accessibility of the metal atom Mto the olefins to be polymerized. It is therefore possible to modify theactivity and selectivity of the catalyst with respect to variousmonomers, in particular bulky monomers. Since the substituents can alsoaffect the rate of termination reactions of the growing polymer chain,they also provide a means of altering the molecular weight of theresultant polymers. The chemical structure of the substituents R¹-R⁸ maytherefore be varied over a wide range in order to achieve the desiredresults and obtain a tailored catalyst system. Examples of possibleorganocarbon substituents R¹-R⁸ are the following: C₁-C₂₀-alkyl, linearor branched, e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tort-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl orn-dodecyl, 5- to 7-membered cycloalkyl, which may in turn have aC₆-C₁₀-aryl substituent, for example cyclopropane, cyclobutane,cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane orcyclododecane, C₂-C₂₀-alkenyl, linear, cyclic or branched, where thedouble bond may be internal or terminal, e.g. vinyl, 1-allyl, 2-allyl,3-allyl, butenyl, pentenyl, hexenyl, cyclopentenyl, cyclohexenyl,cyclooctenyl or cyclooctadienyl, C₆-C₂₀-aryl, where the aryl radical mayhave other alkyl substituents, e.g. phenyl, naphthyl, biphenyl,anthranyl, o-, m-, p-methylphenyl, 2,3-, 2,4-, 2,5-, or2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- or3,4,5-trimethylphenyl, or arylalkyl, where the arylalkyl group may haveother alkyl substituents, e.g. benzyl, o-, m-, p-methylbenzyl, or 1- or2-ethylphenyl, and if desired two groups R¹-R¹⁶ may also have beenbonded to give a 5- or 6-membered ring and the organic radicals R¹-R⁸may have halogen substituents, such as fluorine, chlorine or bromine.Possible radicals for R⁹ in the organosilicon substituents SiR⁹ ₃ arethose described in some detail above for R¹-R⁸, and if desired two R⁹radicals may also have been bonded to give a 5- or 6-membered ring.Examples of SiR⁹ ₃ are trimethylsilyl, triethylsilyl,butyldimethylsilyl, tributylsilyl, triallylsilyl, triphenylsilyl anddimethylphenylsilyl. Preferred radicals R¹-R⁶ are hydrogen, methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl,n-hexyl, n-heptyl, n-octyl, vinyl, allyl, benzyl, phenyl, o-dialkyl- ordichloro-substituted, phenyl groups, trialkyl- or trichloro-substitutedphenyl groups, naphthyl, biphenyl and anthranyl. Particularorganosilicon substituents are trialkylsilyl groups having from 1 to 10carbon atoms in the alkyl radical, in particular trimethylsilyl.Particularly preferred radicals R¹ and R² are methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, allyl, benzyl, phenyl and trialkylsilyl. R³-R⁶ are preferablyhydrogen, methyl, ethyl, n propyl, isopropyl, n-butyl, isobutyl,tert-butyl, n-pentyl, n hexyl, n-heptyl, n-octyl, benzyl or phenyl. I(without Z) is preferably an indenyl group, e.g. indenyl,2-methylindenyl, 2 ethylindenyl, 2-isopropylindenyl, 3-methylindenyl,4-phenylindenyl, 2-methyl-4-phenylindenyl or 4-naphthylindenyl, or abenzindenyl system, e.g. benzindenyl or 2-methylbenzindenyl, and in veryparticular preferred transition metal complexes is an indenyl system.

In a particularly preferred embodiment Z is an unsubstituted orsubstituted 8-quinolyl system and R¹-R⁶ are hydrogen.

The substituents X result, for example, from the selection of theappropriate chromium starting compounds used to synthesize the chromiumcomplexes, but may also still be varied subsequently. Particularsubstituents X are the halogens, such as fluorine, chlorine, bromine oriodine, and among these in particular chlorine. Other advantageousligands X are simple alkyl radicals, such as methyl, ethyl, propyl,butyl, vinyl, allyl, phenyl or benzyl. Other ligands X which may bementioned merely as examples not to the exclusion of others aretrifluoracetate, BF₄—, PF₆—, and also noncoordinating or weaklycoordinating anions (see, for example, S. Strauss in Chem. Rev. 1993,93, 927-942), such an B(C₆F₅)₄—. The term anions when used for theligands X implies no statement as to the nature of the bond to thetransition metal M. For example, if X is a noncoordinating or weaklycoordinating anion the interaction between the metal M and the ligand Xis primarily electrostatic in nature. In contrast, if X is alkyl, forexample, the bond is covalent. The various types of bonds are known tothe skilled worker.

Amides, alcoholates, sulfonates, carboxylates and β-diketonates are alsoparticularly suitable. Varying radicals R⁷ and R⁸ allows fine controlof, for example, physical properties such as solubility. The radicals R⁷and R⁸ used are preferably C₁-C₁₀-alkyl such as methyl, ethyl, n-propyl,n-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or n-octyl, or alsovinyl, allyl, benzyl or phenyl. Some of these substituted ligands X arevery particularly preferred, since they are obtainable from inexpensiveand easily accessible starting materials. In a particularly preferredembodiment, therefore, X is dimethylamide, methanolate, ethanolate,isopropanolate, phenolate, naphtholate, triflate, p-toluenesulfonate,acetate or acetylacetonate.

The number n of ligand X depends on the oxidation state of the chromiumcenter. It is therefore not possible to give a general value for n.Chromium is very probably in the oxidation state +3, but it is alsopossible to use complexes whose oxidation state does not correspond tothat of the active catalyst. Complexes of this type may then be oxidizedor reduced appropriately by suitable activators. Preference is given tothe use of chromium complexes in the oxidation state +3.

The donor Z may have coordinative bonding to the a chromium. This may beintermolecular or intramolecular. The donor Z preferably hasintramolecular coordinative bonding to the chromium, but this may changeduring the course of the polymerization.

The transition metal complex of the formula I may be monomeric, dimericor trimeric, and m is then 1, 2 or 3. It is possible here, for example,for one or more ligands X to bridge two metal centers M.

Examples of preferred complexes are

-   1-(8-quinolyl)indenylchromium(III) dichloride,-   1-(8-quinolyl)-2-methylindenylchromium(III) dichloride,-   1-(8-quinolyl)-2-isopropylindenylchromium(III) dichloride,-   1-(8-quinolyl)-2-ethylindenylchromium(III) dichloride,-   1-(8-quinolyl)-2-tert-butylindenylchromium(III) dichloride,-   1-(8-quinolyl)benzindenylchromium(III) dichloride,-   1-(8-quinolyl)-2-methylbenzindenylchromium(III) dichloride,-   1-(8-(2-methylquinolyl))indenylchromium(III) dichloride,-   1-(8-(2-methylquinolyl))-2-methylindenylchromium(III) dichloride,-   1-(8-(2-methylquinolyl))-2-isopropylindenylchromium(III) dichloride,-   1-(8-(2-methylquinolyl))-2-ethylindenylchromium(III) dichloride,-   1-(8-(2-methylquinolyl))-2-tert.butylindenylchromium(III)    dichloride, 1-(8-(2-methylquinolyl))benzindenylchromium(III)    dichloride or-   1-(8-(2-methylquinolyl))-2-methylbenzindenylchromium(III)    dichloride.

The metal complexes, in particular the chromium complexes, may beattained in a simple manner by reacting the appropriate metal salts,e.g. metal chlorides, with the ligand anion (e.g. in a manner similar tothe examples of DE 197 10615).

The novel olefin polymerization process may be combined with any knownindustrial polymerization process at from 20 to 300° C. and at from 5 to4000 bar. Advantageous ranges of pressure and temperature for carryingout the process are therefore highly dependent on the polymerizationmethod. The catalyst systems used according to the invention may,therefore, be used in any known polymerization process, e.g. inhigh-pressure polymerization in tubular reactors or autoclaves insuspension polymerization, in solution polymerization or in gas-phasepolymerization. In high-pressure polymerization, which is usuallycarried out at from 1000 to 4000 bar, in particular from 2000 to 3500bar, the polymerization temperatures set are also usually high.Advantageous temperature ranges for this high-pressure polymerizationprocess are from 200 to 330° C., in particular from 220 to 270° C. Inlow-pressure polymerization processes the temperature set is usually atleast a few degrees below the softening point of the polymer. Particulartemperatures set in these polymerizations are from 50 to 180° C.,preferably from 70 to 120° C. Suspension polymerization is usuallycarried out in a suspension mediums, preferably in an alkane. Particularalkanes which may form the suspension medium in the polymerization orcopolymerization reaction include the higher olefins, such as propene,butene or hexene in the liquefied or liquid state. The polymerizationtemperatures are generally from −20 to 115° C., and the pressure isgenerally from 1 to 100 bar. The solids content of the suspension isgenerally from 10 to 80%. The operation may be carried out batchwise,e.g. in stirred autoclaves, or else continuously, e.g. in tubularreactors, preferably in loop reactors. The operation may in particularfollow the Phillips PF-process, as described in U.S. Pat. No. 3,242,150and U.S. Pat. No. 3,248,179.

Among the polymerization processes mentioned particular preference isgiven according to the invention to gas-phase polymerization, inparticular in gas-phase fluidized-bed reactors, to solutionpolymerization and also to suspension polymerization, in particular inloop reactors or stirred tank reactors. The gas-phase polymerization mayalso be carried out by the methods of operation known as condensed,supercondensed or supercritical. It is also possible, if desired, fordifferent or identical polymerization processes to be combined in seriesto form a polymerization cascade. It is also possible for an additive,e.g. hydrogen, to be used in the polymerization processes in order toregulate the properties of the polymer.

Some of the metal complexes according to the invention have inthemselves little or no activity for polymerization, and in this casethey are brought into contact with an activator, component (B), so thatthey can develop good activity for polymerization. Examples of possibleactivator compounds are those of aluminoxane type, in particularmethylaluminoxane MAO. Aluminoxanes are prepared, for example, bycontrolled addition of water to alkylaluminum compounds, in particulartrimethylaluminum. Aluminoxane preparations suitable as cocatalyst areavailable commercially. These are assumed to be a mixture of cyclic andlinear compounds. The cyclic aluminoxanes may be given the summarizedformula (R²⁰AlO)_(s) and the linear aluminoxanes may be given thesummarized formula R²⁰(R²⁰AlO)_(s)R²⁰ ₂Al where s is the degree ofoligomerization and is a number from about 1 to 50. Advantageousaluminoxanes essentially comprise aluminoxane oligomers having a degreeof oligomerization of about from 1 to 30, and R²⁰ is preferablyC₁-C₆-alkyl, particularly preferably methyl, ethyl, butyl or isobutyl.

Other activator components which may be used besides the aluminoxanesare those used in the procedure known as cationic activation ofmetallocene complexes. Activator components of this type are disclosed,for example, in EP-B1-0468537 and EP-B1-0427697. Particular activatorcompounds (B) of this type which are used are boranes, boroxines orborates, e.g. trialkylborane, triarylborane, trimethylboroxine,dimethylanilinium tetraarylborate, trityl tetraarylborate,dimethylanilinium boratabenzenes or tritylboratabenzenes (seeWO-A-97/36937). Particular preference is given to the use of boranes orborates in each case having at least two perfluorinated aryl radicals.Particularly suitable activator compounds (B) used are those selectedfrom the group consisting of aluminoxanes, dimethylaniliniumtetrakispentafluorophenylborate, trityl tetrakispentafluorophenylborateand trispentafluorophenylborane.

It is also possible to use activator compounds with more powerfuloxidizing properties, e.g. silver borates, in particular silvertetrakispentafluorophenylborate, or ferrocenium borates, in particularferrocenium tetrakispentafluorophenylborate or ferroceniumtetraphenylborate.

Other activator components which may be used are compounds such asalkylaluminum compounds, in particular trimethylaluminum,triethylaluminum, triisobutylaluminum, tributylaluminum,dimethylaluminum chloride, dimethylaluminum fluoride, methylaluminumdichloride, methylaluminum sesquichloride, diethylaluminum chloride oraluminum trifluoride. It is also possible to use the hydrolysis productsof alkylaluminum compounds with alcohols (see, for example,WO-A-95/10546).

Other activator compounds which may be used are alkyl compounds oflithium, magnesium or zinc, e.g. methylmagnesium chloride,methylmagnesium bromide, ethylmagnesium chloride ethylmagnesium bromide,butylmagnesium chloride, dimethylmagnesium, diethylmagnesium,dibutylmagnesium, methyllithium, ethylithium, methylzinc chloride,dimethylzinc or diethylzinc.

It is sometimes desirable to use a combination of different activators.This is known, for example, in the case of the metallocenes, from whichboranes, boroxines, (WO-A-93/16116) and borates are frequently used incombination with an alkylaluminum compound. It is generally alsopossible to use a combination of different activator components with thetransition metal complex according to the invention.

The amount of the activator compounds to be used depends on the natureof the activator. The molar ratio of metal complex (A) to activatorcompound (B) may generally be from 1:0.1 to 1:10,000, preferably from1:1 to 1:2000. The molar ratio of metal complex (A) to dimethylaniliniumtetrakispentafluorophenylborate, trityl tetrakispentafluorophenylborateor trispentafluorophenylborane is from 1:1 to 1:20, preferably from 1:1to 1:5, particularly preferably from 1:1 to 1:2, and tomethylaluminoxane it is preferably from 1:1 to 1:2000, particularlypreferably from 1:10 to 1:1000. Since many of the activators, e.g.alkylaluminum compounds, are at the same time used to remove catalystpoisons, the amount used of what are known as scavengers depends on thecontamination in the other starting materials. However, the skilledworker can determine the ideal amount by simple tests.

The transition metal complex may be brought into contact with theactivator compound(s) either prior to or after contacting the olefin tobe polymerized. There may also be preactivation with one or moreactivator compounds prior to the mixing with the olefin, and furtheraddition of the same or of other activator compounds once this mixturehas come into contact with the olefin. Preactivation generally takesplace at from 10 to 100° C., preferably from 20 to 80° C.

The catalysts (A) according to the invention may, if desired, also havebeen immobilized on an organic or inorganic support and used insupported for in the polymerization. This is a frequently used method ofavoiding reactor deposits and of controlling the morphology of thepolymer. Preferred support materials are silica gel, magnesium chloride,aluminum oxide, mesoporous materials, aluminosilicates and organicpolymers, such as polyethylene, polypropylene or polystyrene, inparticular silica gel or magnesium chloride.

The activator compounds (B) and the metal complex (A) may be broughtinto contact with the support in a variety of sequences orsimultaneously. This is generally done in an inert solvent which can befiltered off or evaporated after the immobilization. However, it is alsopossible to use the supported catalyst while it in still moist. Forexample, the support may first be mixed with the activator compound(s)or the support may first be brought into contact with the polymerizationcatalyst. It is also possible to preactivate the catalyst with one ormore activator compounds prior to mixing with the support. The amount ofmetal complex (A) (in mol) per gram of support material may vary widely,e.g. from 0.001 to 1. The preferred amount of metal complex (A) per gramof support material is from 0.001 to 0.5 mmol/g, particularly preferablyfrom 0.005 to 0.1 mol/g. In one possible embodiment the metal complex(A) may also be prepared in the presence of the support material.Another type of immobilization is prepolymerization of the catalystsystem with or without prior application to a support.

The novel ethylene copolymer may also be a constituent of a polymermixture. The nature of the other polymer components in the mixturedepends on how this will subsequently be used. The mixture may beprepared, for example, by blending one or more additional LLDPEs orHDPEs or LDPEs. On the other hand the polymer mixture may be prepared bysimultaneous polymerization using a catalyst system which likewise hasactivity for olefin polymerization. Catalysts (c) which may be used herefor preparing the blend polymers and, respectively, for the simultaneouspolymerization are in particular traditional Ziegler Natta catalystsbased on titanium, traditional Phillips catalysts based on chromiumoxides, metallocenes, the complexes known as constrained-geometrycomplexes (see, for example, EP A 0 416 815 or EP a 0 420 436), nickeland palladium bisimine system (for the preparation of which see WO98/03559 A1) or iron and cobalt pyridinebisimine compounds (for thepreparation of which see WO 98/27124 A1). (C) may, however, also beanother chromium complex according to the invention. The polymerizationcatalysts (C) may likewise have been applied to supports.

The novel ethylene copolymer may also form bimodal mixtures with otherolefin polymers, in particular ethyelenehomo- and copolymers. These maybe obtained either by the simultaneous use, as described above, ofanother catalyst suitable for olefin polymerization or by subsequentblending of the polymers and, respectively, copolymers which have beenobtained separately.

The blends which comprise the novel olefin copolymers may furthercomprise two or three other olefin polymers or, respectively, olefincopolymers. These may, for example, be LDPEs (blends of these aredescribed, for example, in DE-A1-19745047) or polyethylene homopolymers(blends of these are described, for example, in EP-B-100843), LLDPEs (asdescribed, for example, in EP-B-728160 or WO-A-90/03414), or LLDPE/LDPE(WO 95/27005 or EP-B1-662989).

The proportion of the novel ethylene copolymer in the total polymermixture is at least 40 to 99% by weight, preferably from 50 to 90% byweight.

The ethylene copolymers, polymer mixtures and blends may compriseauxiliaries and/or additives known per so, such as process stabilizers,stabilizers to protect from the effects of light or heat, customaryadditives, such as lubricants, antioxidants, antiblocking agents andantistats, or also, if desired, dyes. The nature and amount of theseadditives are familiar to the skilled worker.

It has also become apparent that the processing properties of the novelpolymers can be further improved by admixing small amounts offluoroelastomers or of thermoplastic polyesters. These fluoroelastomersare known per se as processing aids and are available commercially, forexample by the trade names Viton® and Dynamar® (see also, for example,U.S. Pat. No. 3,125,547). The amounts of these preferably used are from10 to 1000 ppm, particularly preferably from 20 to 200 ppm, based on thetotal weight of the novel polymer mixture.

The novel polymer may also subsequently be modified by grafting,crosslinking, hydrogenation or other functionalization reactions knownto the skilled worker.

The polymer blends may be prepared by any known process, for example byintroducing the granular component into a pelletizing assembly, e.g. atwin-screw kneader (ZSK) or Farrel kneader. It is also possible for amixture in pellet form to be processed directly on a film productionplant.

An example of a process for which the polymer mixtures are highlysuitable is the production of films on blown film or cast film plants athigh output rates. The film made from the polymer mixtures have verygood mechanical properties, high shock resistance and high tearstrength, together with good optical properties. They are particularlysuitable for the packaging sector, and also for heavy duty sacks, andfor the food and drink sector. The films moreover have only very littletendency toward blocking and can therefore be run on machinery without,or with only very little, addition of lubricants or antiblocking agents.

The good mechanical properties of the olefin copolymers prepared usingthe catalyst system according to the invention also make the suitablefor producing fibers or moldings.

The examples below describe the invention.

Analysis

NMR samples were taken under an inert gas and where appropriate sealedby fusion. The internal standard used in the ¹H and ¹³C NMR spectra werethe solvent signals, and the chemical shift of these was converted toTMS basis. NMR measurements were made on a Bruker AC 200 and, inparticular for COST experiments, on a Bruker AC 300.

Mass spectra were determined on a VG Micromass 7070 H and a Finnigan HAT8230. High-resolution mass spectra were determined on Jeol JMS-700 andVG ZAB 2F equipment.

Elemental analyses were carried out on a Heraeus CHN-O-Rapid.

The comonomer content of the polymer (% C₆), its content of methyl sidechains per 1000 carbon atoms of the polymer chain (CH₃/1000) and itsdensity were determined by IR spectroscopy.

The TREF studies were carried out under the following conditions:solvent: 1,2,4-trichlorobenzene, flow rates 1 ml/min, heating rate 1°C./min, amount of polymer: 5-10 mg, support: kieselguhr.

The η value was determined using an automatic Ubbelohde viscometer(Laude PVS 1) with decalin as solvent at 130° (ISO1628 at 130° C., 0.001g/ml of decalin).

The molar mass distributions and the averages Mn, Mw, Mw/Mn and Mzderived from these were determined by high-temperature gel permeationchromatography by a method based on DIN 55672 under the followingconditions solvents 1,2,4-trichlorobenzene, flow rate: 1 ml/min,temperatures 140° C., calibration with PE standards.

Abbreviations in the tables below:

-   Cat. catalyst (the transition metal complex according to the    invention)-   Sup.cat. supported catalyst-   T temperature during the polymerization-   t duration of the polymerization-   p pressure during the polymerization-   Mw weight-average molar mass-   Mn number-average molar mass-   mp melting point-   b Staudinger index (viscosity)-   Density polymer density-   CH₃/1000 number of methyl side chains per 1000 carbon atoms % C₆    comonomer content of the polymer in t by weight    General Synthesis Specification:

EXAMPLE 1 1-(8-quinolyl)indenylchromium(III) Dichloride

1.1. Preparation of 1-(8-quinolyl)indene

10.4 g (50 mmol) of 8-bromoquinoline in 100 ml of THF were cooled toabout −100° C. 20 ml of n-BuLi (2.5M in hexane, 50 mmol) were addeddropwise within a period of 5 min while the internal temperature washeld below −80° C. After this addition stirring was continued at −80° C.for a further 15 min, and 6.6 g of 1-indanone (50 mmol) dissolved in 30ml of THF were then added dropwise within a period of 10 min. Thereaction mixture was then allowed to reach room temperature graduallyand was then heated for 3 b at reflux. Once the mixture had cooled toroom temperature, ice was added, followed by hydrochloric acid until thepH was about 1, followed by stirring for 30 min. The aqueous and organicphase were separated. The aqueous phase was mixed with ammonia solutionuntil the pH was about 9 and extracted with ether. The combined organicphases were then evaporated to dryness in vacuo. The resultant viscousoil (1-(8-quinolyl)indan-1-ol (8H₂O)) vas mixed with hydrochloric aciduntil the pH was 0, heated at reflux for 2 hours and then neutralised.After work-up and drying it was possible to isolate 6.6 g of1-(8-quinolyl)indene (55%) as a colorless solid.

1-(8-quinolyl)-indan-1-ol (8H₂O)

¹H NMR: (200 Mhz, CDCl₂) δ=2.58-2.87 (m, 3H, CH₂); 6.94 (dd, 1H,quinoline CH): 7.24-7.36 (m, 4H, CH): 7.44-7.50 (m, 2H, H3, H6); 7.70(dd, 1H, quinoline CH); 8.23 (dd, 1H); 8.66 (s, br, 1H, OH); 8.92 (dd,1H).

¹²C NMR: (200 MHz, CDCl₃) δ=30.2, 44.8 (CH₂); 87.2 (COH); 120.8, 124.7,125.1, 126.4, 126.9, 127.2, 127.5, 128.2, 137.9, 147.7 (CH); 127.4,129.2, 142.6, 143.8, 146.7 (quart. C).

1-(8-quinolyl)inden

m.p.: 108° C.

¹H-NMR: (200 MHz, CDCl₃) δ=3.69 (d, 2H, CH₂); 6.80 (t, 1H, ═CH);7.12-7.26 (m, 3H); 7.41 (dd, 1H); 7.55-7.64 (m, 2H); 7.81-7.88 (m, 2H);8.21 (dd, 1H); 8.92 (dd, 1H).

¹³C-NMR: (50 MHz, CDCl₃) δ=38.8 (CH₂); 121.0, 121.2, 123.8, 124.5,125.8, 126.3, 127.8, 130.0, 133.5, 136.1, 150.0 (CH); 128.6, 135.9,143.7, 144.0, 145.6, 146.7 (quartz. C).

MS (EI): m/z (%)=243 (65) [M⁺]; 242 (100) [M⁺−H].

HR-MS (EI): 243.1048 (calc.), 243.1038 (found).

C,H,N analysis: calc. 88.86% C, 5.39% H, 5.75% N

-   -   found: 87.55% C, 5.52% H, 5.92% N.        1.2. Preparation of dichloro[1-(8-quinolyl)indenyl]chromium        (III):

0.05 g of potassium hydride (1.23 mmol) were suspended in 20 ml of THFand 0.3 g of 1-(8-quinolyl)indene (1.23 mol) were slowly added. Theresultant violet suspension was stirred for three hours at roomtemperature and then added dropwise to a mixture of 0.46 g ofchromium(III) chloride 3THF (1.23 mmol) in 50 ml of THF. Once thisaddition was complete the mixture was stirred for a further 16 hours.The solvent was removed in vacuo and the resultant solid extractedseveral times with hot toluene on a G4 frit. Once the solvent had beendistilled off from the combined extracts the product was obtained as agreen powder. This was washed several times with hexane and dried underHV, giving 0.22 g of dichloro[1-(8-quinolyl)indenyl]chromium(III) (50%).

Another method is to take up the residue in methylene chloride, separateoff potassium chloride and remove the solvent, thus again obtaining thechromium complex.

MS (EI): m/z (%)=364 (0.2, M⁺); 329 (0.1, M⁺−Cl); 242 (100, Ind(quinoline)⁺)

HR-EI-MS: 363.97519 (calc.), 363.97615 (meas.)

EXAMPLES 2 And 3

Copolymerization of Ethene with 1-hexene

The polymerization experiments were carried out in a 1 l four-neckedflask with a contact thermometer, a stirrer with teflon blade, a heatingmantle and a gas inlet tube. The initial charge used, at 40° C. underargon, was the amount given in Table 1 ofdichloro[1-(8-quinolyl)indenyl]chromium(III) in 250 ml of toluene. Theamount of 1.6 M MAO solution in toluene added during the activation withMAO in each case is given in Table 2.

5 ml of hexene formed an initial charge prior to ethylene addition, andabout 20 to 40 l/h of ethylene were then passed through at atmosphericpressure for one hour. The remaining amount of hexene was fed within aperiod of 15 min via a dropping funnel.

The reaction was terminated by adding a mixture made from 15 ml ofconcentrated hydrochloric acid and 50 ml of methanol and stirring wasthen continued for 15 in. After adding a further 250 ml of methanol andstirring for 15 ml the product was filtered off, washed three times withmethanol and dried at 70° C. Table 1 gives the data for thepolymerization and the product.

TABLE 1 Data for polymerization and product in Examples 2 and 3 Cat.amount. MAO Hexene T Activity Yield Density η Ex. [mg] (μmol) [mmol]Al:Cr Cr:B [ml] [° C.] [kg/molCr · h] [g] ([min]) [g/cm³] [dl/g] 2 6.1(16.7) 8.5 510 — 30 60 1400 23.4 (60′) 0.881 2.15 3 5.8 (15.8) 8 500 —30 52 1020 16.1 (60′) 0.884 6.44 CDBI Ta Density Eta Mw Mn Mw/Mn C6 m.p.CH₃ Ex. [%] [° C.] σ [g/cm³] [dl/g] [g/mol] [g/mol] — [%] [° C.] [/1000°C.] 2 90 53.2 9.9 0.881 2.15 132567  49540 2.68 20 61.3 37.1 3 95 59.311.6 0.884 6.44 740298 224534 3.3 13 90.9 23.5

1. A copolymer of ethylene with C₃-C₉-α-olefins, which has apolydispersity M_(w)/M_(n) of from 2 to 10, a density of from 0.85 to0.93 g/cm³, a proportion of from 10 to 40% by weight of comonomer and amolar mass M_(n) above 150,000 g/mol and a comonomer compositiondistribution index above 70%.
 2. The copolymer as claimed in claim 1,wherein said density is from 0.88 to 0.93 g/cm³.
 3. The copolymer asclaimed in claim 1, wherein said comonomer composition distributionbreadth index is above 90%.
 4. The copolymer as claimed in claim 1,wherein said α-olefins are selected from the group consisting ofpropene, 1-butene, 1-hexene and 1-octene.
 5. The copolymer as claimed inclaim 1, wherein said polydispersity Mw/Mn is from 2 to
 4. 6. Thecopolymer as claimed in claim 1, wherein said molecular weight Mn isabove 200,000 g/mol.
 7. A polymer mixture which comprises said at leastone of the copolymer of ethylene with C₃-C₉-α-olefins as claimed inclaim
 1. 8. A fiber, a film or a molding which comprises the copolymerof ethylene with C₃-C₉-αolefins as claimed in claim
 1. 9. A fiber, afilm or a molding which comprises the copolymers of ethylene withC₃-C₁₂-α-olefins as claimed in claim
 1. 10. The copolymer of claim 2,wherein the comonomer composition distribution breadth index is above90%, the α-olefins are selected from the group consisting of propene,1-butene, 1-hexene and 1-octene, polydispersity M2/Mn is from 2 to 4 andmolecular weight Mn is above 200,000 g/mol.
 11. The copolymers of claim10 wherein the comonomer is hexene-1.
 12. The copolymer of claim 11wherein the CDBI is about 95%.
 13. The copolymer of claim 11 wherein thedensity is about 0.88, the CDBI is about 95% and the polydispersityMw/Mn is about
 3. 14. The copolymer of claim 13 wherein the density is0.884, the CDBI is 95%, the molecular weight Mn is about 224,000 and thepolydispersity is 3.3.